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I have some text file types that do not show their contents when I use the space preview feature on Mac. For example, the markdown files (md) show their content correctly, but dart files (dart) do not show their content even though they are just text source files. The attached screen capture shows the content in the Preview box for the markdown, but not for the dart.

I also found that some files such as yaml and lock files have the same problem.

How to solve this issue? How can I teach Mac that dart, yaml, and lock files are not binary, but text files?

3 Answers 3


Quick Look has no way of telling that these files are text or not, and requires a Quick Look Extension. Quick Look Extensions provide the previews you see when you hold down space, but for file formats that aren't supported by default. You can use one such as Glance or Peek, and there are several others available.

  • 1
    Peek costs a lot of money, and glance has some glitches, in my experience. I reccomend the various single-purpose plugins the open-source community has created, such as qlstephen in this case. Commented Apr 19, 2022 at 22:52
  • It's such a shame for OSX 12.2 (Monterey) and Apple AD 2022 you need to install third party app for previewing yaml or mardkown; I go for Peek. work very nice with two mentioned file types.
    – andilabs
    Commented Jan 8, 2023 at 23:33

QuickLook stephen is a simple, set-it-and-forget-it, open-source extension that can be installed via homebrew or by dropping a file in a folder. It allows quicklook to display text files with no/unknown extensions, like readme files (exactly what you need).

  • Noticing the downvote, is there anything i can do to improve my answer? Commented May 8, 2022 at 0:42

Another option is Awesome list of useful Quick Look plugins for developers

  • Why is this an option and how does it solve the problem described in the question?
    – nohillside
    Commented Aug 7, 2023 at 16:34
  • This is option because Quick Look plugins change behavior of Mac on space bar action. Commented Aug 15, 2023 at 7:13

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